138. Biatorella] 36. ACAROSPORACEAE 279 



5. Thelocarpon epilithellum Nyl., Flora 48:605, 606. 1865. 



Thallus rudimentary, the superficial portion absent or scarcely visible ; apothecia 

 minute, 0.05-0.1 mm. across, globose, scattered or rarely aggregate, entirely covered 

 by a thin, greenish yellow, thalloid exciple except a tiny black pore at the depressed 

 apex; hyaline within; paraphyses slender, short; asci long, cylindrical to broadly 

 distended toward the center; spores oblong, 3.5-6 X 1.5-2.5 fi. 



On rocks, Illinois. 



6. Thelocarpon prasinellum Nyl., Flora 64:451. 1881. 



Thallus rudimentary, the superficial portion a very thin greenish crust over the 

 substratum, commonly disappearing; apothecia minute, 0.1-0.2 mm. across, globose, 

 scattered, entirely covered by a thin, greenish, thalloid exciple except a minute 

 black pore at the apex; hyaline within; paraphyses slender and branched; asci 

 cylindrical, becoming distended toward the center; spores oblong-ellipsoid, 4-7 X 

 2.5-4 /a. 



On old wood and rocks, Massachusetts, Ohio, Iowa, and Minnesota. 



7. Thelocarpon superellum Nyl., Flora 48:261, 262. 1865. 



Thallus rudimentary, the superficial portion absent or scarcely visible; apothe- 

 cia minute, 0.05-0.15 mm. across, globose, scattered, entirely covered by a thin, 

 greenish yellow, thalloid exciple except a minute pore at the subcorneal apex; 

 hyaline within; paraphyses slender, threadlike; asci distended toward the middle; 

 spores small, oblong or oblong-ellipsoid, non-septate or appearing 1 -septate, 8-12 

 X 3^.5 ix. 



On old wood, New Hampshire, Massachusetts, and New York. 



OTHER SPECIES REPORTED 

 Thelocarpon albomarginatum Herre — California. 



138. Biatorella De Not., Giorn. Bot. Ital. 2 1 : 192. 1846. 



Thallus crustose, often inconspicuous and evanescent, but sometimes granular, 

 warty, or subareolate, devoid of differentiation and attached to the substratum by 

 hyphal rhizoids; apothecia usually minute to small, immersed to sessile, the disk 

 flat to convex, the exciple colored like the disk, sometimes becoming covered; 

 hypothecium hyaline to brown; hymenium hyaline to brown; paraphyses un- 

 branched or inconspicuously branched, often somewhat enlarged above; asci broad- 

 ly clavate or ventricose; spores minute and numerous, rarely only 12 or 8, hyaline, 

 non-septate, spherical to oblong or ellipsoid. 



The algal host is Pleurococcus. 



A. On trees, old wood, soil, and over moss 

 B. On trees 



C. Spores spherical 



D. Thallus yellowish or orange-yellow 



E. Thallus lemon-yellow 3. B. nannaria 



E. Thallus yellowish gray to orange-yellow .... 5. B.conspersa 

 D. Thallus greenish gray to whitish or brownish 



E. Thallus minutely granulose 6. B. moriformis 



E. Thallus very thin, smooth 4. B. Rappii 



C. Spores oblong to short-ellipsoid 

 D. Apothecia 0.4-0.9 mm. across 



E. Spores 5-11 X 2-2.5 /i 15. B. camptocarpa 



E. Spores 3-4 X 2-3 /a 14. B. cyphalea 



D. Apothecia 0.05-0.1 mm. across 13. B.albidula 



B. On old wood and soil and over moss 

 C. Spores spherical 



D. Apothecia 0.15-0.3 mm. across 1. B. geophana 



D. Apothecia 0.4-1 mm. across 2. B.resinae 



C. Spores oblong to oblong-cylindrical or ellipsoid 



D. Apothecia 0.2-0.5 mm. across 8. B.campestris 



D. Apothecia 0.7-1 mm. across 9. B. fossarum 



